Merge "Cache Max Subsample Size" into rvc-dev

libwvdrmengine/cdm/core/include/crypto_session.h

@@ -300,7 +300,7 @@ class CryptoSession {
   CdmResponseType GetSystemIdInternal(uint32_t* system_id);
   CdmResponseType GenerateRsaSignature(const std::string& message,
                                        std::string* signature);
-  bool GetMaxSubsampleRegionSize(size_t* max);
+  size_t GetMaxSubsampleRegionSize();
 
   bool SetDestinationBufferType();
 
@@ -429,6 +429,7 @@ class CryptoSession {
   static std::atomic<uint64_t> request_id_index_source_;
 
   uint32_t api_version_;
+  size_t max_subsample_region_size_;
 
   // Stores the most recent error code returned from a call to
   // OEMCrypto_DecryptCENC.  This is used to reduce the total number of

libwvdrmengine/cdm/core/src/crypto_session.cpp

@@ -80,7 +80,7 @@ static_assert(ArraySize(kMaxSubsampleRegionSizes) ==
               "The kMaxSubsampleRegionSizes table needs to be updated to "
               "reflect the supported range of resource rating tiers.");
 
-constexpr size_t kDefaultMaximumChunkSize = 100 * KiB;
+constexpr size_t kDefaultMaxSubsampleRegionSize = kMaxSubsampleRegionSizes[0];
 
 // This maps a few common OEMCryptoResult to CdmResponseType. Many mappings
 // are not universal but are OEMCrypto method specific. Those will be
@@ -217,7 +217,8 @@ CryptoSession::CryptoSession(metrics::CryptoMetrics* metrics)
       requested_security_level_(kLevelDefault),
       usage_support_type_(kUnknownUsageSupport),
       usage_table_header_(nullptr),
-      api_version_(0) {
+      api_version_(0),
+      max_subsample_region_size_(0) {
   assert(metrics);
   Init();
   life_span_.Start();
@@ -1331,14 +1332,28 @@ CdmResponseType CryptoSession::GenerateRsaSignature(const std::string& message,
                             "OEMCrypto_GenerateRSASignature");
 }
 
-bool CryptoSession::GetMaxSubsampleRegionSize(size_t* max) {
-  uint32_t tier = 0;
-  if (!GetResourceRatingTier(&tier)) return false;
-  // Subtract RESOURCE_RATING_TIER_MIN to get a 0-based index into the table.
-  const uint32_t index = tier - RESOURCE_RATING_TIER_MIN;
-  if (index >= ArraySize(kMaxSubsampleRegionSizes)) return false;
-  *max = kMaxSubsampleRegionSizes[index];
-  return true;
+size_t CryptoSession::GetMaxSubsampleRegionSize() {
+  // If we haven't cached the answer yet, fetch it from OEMCrypto.
+  if (max_subsample_region_size_ == 0) {
+    uint32_t tier = 0;
+    if (GetResourceRatingTier(&tier)) {
+      // Subtract RESOURCE_RATING_TIER_MIN to get a 0-based index into the
+      // table.
+      const uint32_t index = tier - RESOURCE_RATING_TIER_MIN;
+      if (index < ArraySize(kMaxSubsampleRegionSizes)) {
+        max_subsample_region_size_ = kMaxSubsampleRegionSizes[index];
+      }
+    }
+
+    // If something went wrong, use the default.
+    if (max_subsample_region_size_ == 0) {
+      LOGW("Unable to get maximum subsample region size. Defaulting to %zu.",
+           kDefaultMaxSubsampleRegionSize);
+      max_subsample_region_size_ = kDefaultMaxSubsampleRegionSize;
+    }
+  }
+
+  return max_subsample_region_size_;
 }
 
 CdmResponseType CryptoSession::Decrypt(
@@ -2723,12 +2738,7 @@ OEMCryptoResult CryptoSession::DecryptSample(
 OEMCryptoResult CryptoSession::LegacyDecrypt(
     const OEMCrypto_SampleDescription& sample, CdmCipherMode cipher_mode,
     const OEMCrypto_CENCEncryptPatternDesc& pattern) {
-  size_t max_chunk_size;
-  if (!GetMaxSubsampleRegionSize(&max_chunk_size)) {
-    LOGW("Unable to get maximum subsample region size. Defaulting to 100 KiB.");
-    max_chunk_size = kDefaultMaximumChunkSize;
-  }
-
+  const size_t max_chunk_size = GetMaxSubsampleRegionSize();
   OEMCryptoResult sts = OEMCrypto_ERROR_NOT_IMPLEMENTED;
 
   // We can be sure this is only called with one subsample containing one